Infrared radiation detectors are often used to provide a non-contact temperature indication or to provide a system control input based on surface temperature or environmental radiation. In some applications, the heat flux which is sensed or the surface temperature indication to which that heat flux is converted may not be the ultimate property of interest. For example, it has been demonstrated in U.S. Pat. No. 5,017,019 that surface temperature detected by a radiation sensor can provide an indication of subcutaneous injury of an animal; however, the actual surface temperature should be normalized by a separate ambient temperature indication in order to provide a meaningful indication of the injury. As another example, ear temperature detectors which view the infrared radiation received from the ear canal may be compensated by an ambient temperature indication in order to provide a core temperature reading as suggested in U.S. Pat. No. 4,993,419.
Climate control systems commonly used for controlling heating and/or cooling in automobiles, homes, offices, factories and industrial processing chambers have typically sensed the air temperature of the enclosed space and controlled a heating and/or cooling system to maintain the air temperature at a preselected value. However, more advanced climate control systems which have been suggested sense multiple thermal characteristics including inside air temperature of an enclosed space, solar radiation, occupant body temperature through a radiation detector and external air temperature.